Olbia is a city and comune of 60,346 inhabitants (May 2018) in the Italian insular province of Sassari in northeastern Sardinia (Italy), in the historical region of Gallura. Called Olbia in the Roman age, Civita in the Middle Ages (Judicates period) and Terranova Pausania before the 1940s, Olbia was again the official name of the city during the fascist period.

It is the economic centre of this part of the island (commercial centres, food industry) and is very close to the Costa Smeralda tourist area. It was one of the administrative capitals of the province of Olbia-Tempio, operative since 2005 and canceled after a referendum seven years later. Olbia is a tourist destination thanks to its sea and beaches and also for the large number of places of cultural interest to visit.

Main sights include:

• Romanesque former cathedral of San Simplicio (11th-12th century).
• Church of St. Paul Apostle (medieval)
• National Archaeology Museum
• Pedres Castle
• Several dolmens and a menhir
• Several nuraghes
• Remains of the Roman forum and aqueduct
• Remains of Carthaginian walls
• Fausto Noce park, the largest in Sardinia
• River park of Padrongianus